A projection display apparatus, such as a liquid crystal projector and a CRT projector, has a light source and an optical part that receives light from the light source. Heat generated in the light source raises the temperatures of the light source and the optical part. The projection display apparatus is therefore provided with an air inlet and an air sucking fan for cooling the light source and the optical part.
The air inlet of some of projection display apparatus is formed through a side surface of an enclosure having a substantially box shape. It is, however, difficult to ensure a sufficient opening area of the air inlet formed through a side surface portion of the enclosure. Further, a duct through which air passes needs to be provided between the air inlet and the air sucking fan, disadvantageously preventing the size of the apparatus from being reduced.
To ensure a sufficient opening area of the air inlet, JP-A-2004-157347 proposes a projection display apparatus having an air inlet provided through a bottom surface portion of an enclosure.
How to use a projection display apparatus is classified into the following two ways: A projection display apparatus is either installed on a table or any other installation surface with a top surface portion of the projection display apparatus oriented upward or hung from a ceiling or any other hang surface with a bottom surface portion of the projection display apparatus oriented upward. When a projection display apparatus is hung from a ceiling or any other hang surface with the bottom surface portion oriented upward, the top surface portion designed to be seen is oriented downward and provides a good appearance.
Further, an optical part in a projection display apparatus is typically so disposed that an optical system is oriented obliquely upward (tilt projection) when the projection display apparatus is installed on an installation surface and used. A projection display apparatus hung with the top surface portion thereof oriented upward therefore needs to be so inclined that video images are normally projected on a screen, resulting in a problem because it is difficult to correct trapezoidal distortion of the video images projected from the inclined apparatus.
On the other hand, a projection display apparatus hung with the bottom surface portion thereof oriented upward, which allows the optical system to be oriented obliquely downward, can normally project video images on the screen without having to be inclined. For the reason described above, a typical projection display apparatus, when hung from a hang surface before use, is so installed that the bottom surface portion is oriented upward.